Soil aeration device

ABSTRACT

A soil aeration apparatus may include aeration tines that are actuated by a relatively compact gear system that reduces the size and weight of the apparatus. In addition, a soil aeration apparatus may operate without a centrally disposed support shaft, thus enabling the tine-holder shafts to be positioned closer to one another and reducing the size of the apparatus.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/861,880 filed on Sep. 26, 2007 by David Maas et al. and entitled“Soil Aeration Device,” which is a division of U.S. patent applicationSer. No. 10/775,540 filed on Feb. 10, 2004 by David Maas et al. andentitled “Soil Aeration Device” (now U.S. Pat. No. 7,290,619), which isa continuation-in-part of U.S. patent application Ser. No. 10/638,953filed on Aug. 11, 2003 by David Maas et al. and entitled “Soil Aerator”(now U.S. Pat. No. 7,055,617). The entire contents of these earlierdocuments are incorporated herein by reference.

BACKGROUND

Soil aeration is a conventional technique used by groundskeepers toreduce compaction in the ground soil, stimulate plant growth, andpromote proper drainage. Soils may become compacted from overuse orenvironmental effects, which ultimately affects the soil permeabilityand development of rooted plants within the soil. In particular,compacted soil restricts the amount of oxygen that can enter the soiland the amount of carbon dioxide that can escape. Not all grounds areaffected equally by overuse and environmental factors. The amount ofcompaction depends soil texture, the amount of vegetation, and themoisture content of the soil. Periodic soil aeration relieves thecompaction in the soil before the negative effects overburden the soilto the point that it can no longer support desirable vegetation.

In general, soil aerators have aeration tubes that penetrate the groundand remove “plugs” of soil. The aeration tubes are typically carried onbars or racks that are affixed to a rotary member. The rotor, racks, andassociated gear hardware are typically large, bulky, and heavy. Theoverall dimensions and weight of the aeration device are accordinglyincreased. That, in turn, necessitates the use of relatively largetractors with large displacement engines. Consequently, most aerationdevices are expensive to operate and ill-suited for residential, lightcommercial, or rental use.

SUMMARY

A soil aeration apparatus may include aeration tines that are actuatedby a relatively compact gear system, which reduces the size and weightof the aeration apparatus. In an illustrative embodiment, a soilaeration apparatus includes at least two tine-holder shafts rotatablymounted to a carrier and aeration tines attached to each shaft. Theapparatus may also include a gear system for rotating the tine-holdershafts while the tine-holder shafts revolve about a central axis of thecarrier. The gear system may have a planetary gear coupled to eachtine-holder shaft and a sun gear axially aligned with the central axissuch that each sun gear engages a plurality of planetary gears.

In various embodiments, a soil aeration apparatus may operate without acentrally disposed support shaft, thus enabling the tine-holder shaftsto be positioned closer to one another and reducing the size of theapparatus. In one illustrative embodiment, a soil aeration apparatus mayinclude a carrier rotatably attached to a frame such that the carrier isrotatable about a central axis. The apparatus may also include first andsecond two tine-holder shafts rotatably mounted to the carrier andaeration tines attached to each shaft. A non-centrally located supportshaft may be coupled to the carrier and offset from the central axis andmounted to the carrier. The first and second shafts may be offset fromthe central axis such that the tines are operative to move through thecentral axis without interference from another tine or shaft.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a soil aeration apparatus in accordancewith an embodiment of the invention.

FIG. 2 is a perspective view of a frame for housing the soil aerationapparatus of FIG. 1, with certain components of the frame removed.

FIG. 3 is a perspective view of a soil aeration apparatus in accordancewith another embodiment of the invention.

FIG. 4 is a side view of the soil aeration apparatus of FIG. 3.

FIG. 5 is a perspective view of a frame for housing the soil aerationapparatus of FIG. 4, with a side panel removed from the frame.

FIG. 6 is a perspective view of the soil aeration apparatus of FIG. 1and the soil aeration apparatus of FIG. 3.

FIG. 7A is a side view of the carrier, shafts, and tines of the soilaeration apparatus of FIG. 3, in accordance with an embodiment of theinvention.

FIG. 7B is a front view of a portion of the shafts and tines of the soilaeration apparatus of FIG. 7A.

FIGS. 8A-C are side views of a soil aeration tine forming an aerationpocket in accordance with an embodiment of the invention.

FIG. 9 is a side view of the soil aeration apparatus of FIG. 3 inaccordance with another embodiment of the invention.

FIG. 10 is a side view of the soil aeration apparatus of FIG. 3 inaccordance with yet another embodiment of the invention.

FIG. 11 is a perspective view of an aeration tine that may be used witha soil aeration apparatus in accordance with an embodiment of theinvention.

FIGS. 12A-B are top views of ground surfaces having soil aerated inaccordance with certain embodiments of the invention.

FIG. 13A is a perspective view of the soil aerator frame of FIG. 5, witha side panel removed from the frame to view the soil aeration apparatus.

FIG. 13B is a perspective view of a portion of the soil aerator frame ofFIG. 13.

FIG. 14 is a side view of the soil aeration apparatus from FIG. 13having arcuate tines contacting a ground surface.

FIG. 15 is a side view of an aeration blade from FIG. 14.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1, a soil aeration apparatus 10 includes twotine-holder shafts 30 and 40 extending between opposing carriers 20 and22. The shafts 30 and 40 are rotatably mounted to the carriers 20 and 22such that each shaft may rotate 68 about its own axis. The shafts 30 and40 are positioned substantially parallel in the axial direction, andsoil aeration tines 50 extend from each shaft 30 and 40 in the radialdirection. The soil aeration tines 50 may penetrate and remove a portionof soil from a ground surface as is taught, for example, in U.S. Pat.No. 6,513,603 issued to Bjorge on Feb. 4, 2003, the contents of whichare herein incorporation by reference. Two non-centrally located supportshafts 24 and 26 also extend between the opposing carriers 20 and 22.The support shafts 24 and 26 are fixedly mounted to the carriers 20 and22 and provide mechanical support for the soil aeration apparatus 10when in operation. A gear system 60 is engaged with the tine-holdershafts 30 and 40 to cause rotation of the tine-holder shafts 30 and 40.The gear system 60 has a plurality of planetary gears 63 and 64 for eachsun gear 65. Each shaft 30 or 40 has a planetary gear 63 or 64 attachedthereto. In this embodiment, the sun gear 65 is positioned between theplanetary gears 63 and 64 and is engaged with the planetary gears 63 and64 using a drive chain 66. Because a plurality of planetary gears 63 and64 are operated using an individual sun gear 65, the bulkiness of thegear system 60 is advantageously reduced. Furthermore, because theapparatus 10 does not use a centrally located support shaft, thetine-holder shafts 30 and 40 may be positioned closer to one another,thus reducing the overall size of the apparatus 10.

Referring to FIG. 1 in more detail, bearings 32 and 42 may be used torotatably mount the shafts 30 and 40, respectively, to the carriers 20and 22. The bearings 32 and 42 may comprise ball bearings, rollerbearings, or bushings, and may provide access for a portion of theshafts 30 and 40 to extend through the carriers 20 and 22. The planetarygear 63 is axially aligned with the shaft 30 and fixedly mounted to theportion of the shaft 30 on the outer side of the carrier 20. Similarly,the planetary gear 64 is axially aligned with the shaft 40 and mountedto the portion of the shaft extending through the carrier 20. In thisembodiment, the planetary gears 63 and 64 are radially aligned with thesun gear 65 such that a single drive chain 66 is engaged with all threegears 63, 64, and 65. Briefly describing the operation of the gearsystem 60, the carriers 20 and 22 are motivated to rotate about acentral axis 21 using a drive means (not shown in FIG. 1). The sun gear65 is axially aligned with the central axis 21 but remains substantiallyfixed with respect to the central axis as the carriers 20 and 22 rotate.When the carriers 20 and 22 rotate, the tine-holder shafts 30 and 40 arecaused to revolve around the central axis 21. Likewise, the planetarygears 63 and 64 also revolve around the central axis 21. As such, theplanetary gears 63 and 64 revolve about the sun gear 65 in a direction28 as the drive chain 66 causes the planetary gears 63 and 64 to rotatein a direction 68. The motion of revolving 28 the shaft 30 or 40 aboutthe central axis 21 while rotating 68 the shaft 30 or 40 about its ownaxis causes the desired motion of the tines 50 to penetrate and remove aportion of soil from the ground surface.

Still referring to FIG. 1, the support shafts 24 and 26 are positionedbetween the carriers 20 and 22 and fixedly mounted to near the perimeterof each carrier 20 and 22. Because the support shafts 24 and 26 arenon-centrally located (e.g., offset from the central axis 21),tine-holder shafts 30 and 40 may be positioned closer to the centralaxis 21 without interference from the tines 50 hitting a centrallylocated shaft. Rather, the tine-holder shafts 30 and 40 may rotate inthe direction 68 as the tines 50 pass through the central axis 21without interference. The compact arrangement of shafts 30, 40, 24, and26 advantageously reduces the overall size of the soil aerationapparatus 10 in comparison to other apparatus that require thetine-holder shafts 30 and 40 to be spaced apart for clearance betweenthe revolving tines 50 and a centrally located support shaft.

Referring to FIG. 2, the soil aeration apparatus 10 may be installed ina frame 12. The frame 12 may have a safety panel 13 to prevent damage tothe tine-holder shafts 30 and 40 from debris and to protect a user fromthe moving tines 50 and tine-holder shafts 30 and 40. The frame 12 mayalso include side panels 14 to protect the gear system 60 from debris.In the embodiment shown in FIG. 2, one side panel 14 is removed tobetter show the soil aeration apparatus within the frame 12. Optionally,the sun gear 65 may be attached to the side panel 14 (removed from theview show in FIG. 2) to maintain the sun gear 65 in a substantiallyfixed relationship with respect to the central axis 21. The carriers 20and 22 may be rotatably attached to the side panels 14 or other part ofthe frame 12 such that the carriers 20 and 22 may rotate about thecentral axis 21 while the frame 12 remains substantially fixed withrespect to the central axis 21. A set of wheels (not shown in FIG. 2)may be connected to the side panels 14 or other part of the frame 12.Additionally, the frame may include other components that enable theframe 12 to be attached to a tractor or other vehicle.

Referring to FIG. 3, another embodiment of a soil aeration apparatus 110includes four tine-holder shafts 130, 135, 140, and 145 extendingbetween two carriers 120 and 122. Soil aeration tines 50 extend in asubstantially radial direction from each shaft 130, 135, 140, and 145and are capable of penetrating and removing a portion of soil from theground surface. The shafts 130, 135, 140, and 145 extend substantiallyparallel to one another in the axial direction between the carriers 120and 122. The shafts 130, 135, 140, and 145 are rotatably mounted to thecarriers 120 and 122 using bearings 132, 137, 142, and 147,respectively. As such, each tine-holder shaft 130, 135, 140, or 145 mayrotate about its own axis in a direction 168 while all the shafts 130,135, 140, and 145 revolve in a direction 128 around a central axis 121.The bearings 132, 137, 142, and 147 may comprise ball bearings, rollerbearings, or bushings, and may provide access for a portion of theshafts 130, 135, 140, and 145 to extend through the carriers 120 and122.

Referring to FIGS. 3 and 4, the soil aeration apparatus 110 includes agear system 160 having a plurality of planetary gears 163, 164 (or 173,174) for each sun gear 165 (or 175). In this embodiment, planetary gears163 and 164 interact with sun gear 165. Planetary gear 163 is axiallyaligned with and fixedly mounted to tine-holder shaft 130. Likewise,planetary gear 164 is axially aligned with and fixedly mounted totine-holder shaft 140. The sun gear 165 is axially aligned with thecentral axis 121 but remains substantially fixed with respect to thecentral axis 121 as the carriers 120 and 122 rotate about the centralaxis 121. A drive chain 166 is engaged with the sun gear 165 and thecorresponding planetary gears 163 and 164, which causes the planetarygears 163 and 164 to rotate in the direction 168 as the planetary gears163 and 164 revolve about the sun gear 165 in the direction 128. Thisrotational 168 and revolving 128 motion of the planetary gears 163 and164 causes the tine-holder shafts 130 and 140 to move in a desired pathfor penetrating and removing portions soil from the ground surface.Planetary gears 173 and 174 interact with sun gear 175 by way of a drivechain 176 in a manner similar to that of sun gear 165 and planetarygears 163 and 164. The interaction of planetary gears 173 and 174 withthe sun gear 175 causes the tine-holder shafts 135 and 145 to have arotational 168 and revolving 128 motion similar to that of tine-holdershafts 130 and 140. The gear system 160 provides the desired motion ofthe tine-holder shafts 130, 135, 140, and 145 without using individualsun gear and planetary gear for each tine-holder shaft (e.g., fourtine-holder shafts, four sun gears, and four planetary gears). Rather,the gear system 160 operates a plurality of planetary gears from eachsun gear, which advantageously reduces the bulkiness of the gear systemof the soil aeration apparatus.

Referring to FIG. 5, the soil aeration apparatus 110 may be installed ina frame 112 that transports the apparatus over a ground surface. Theframe may include a safety panel 113 and side panels 114, as previouslydescribed in connection with FIG. 2. In this embodiment, a side panel114 is removed to better show the soil aeration apparatus 110 housed inthe frame 112. In addition, the frame may include wheels 116 and aconnection means 117 so that the frame 112 may be attached to a tractoror other vehicle and moved over the ground surface, for example, asdescribed in connection with FIGS. 13-15. The frame 112 may also includea lifting device 115, such as a pneumatic or hydraulic cylinder, to liftthe soil aeration apparatus 110 from the ground surface while the frameis turning or moving over a non-soil surface. For example, while theconnection means is attached to a vehicle, the cylinder 115 may beactuated to extend the cylinder piston, thereby causing the frame 112 torevolve counterclockwise about a pivot axis P. Such cylinder actuationwill cause the soil aeration apparatus 110 to lift from the groundsurface as the frame 112 rocks back on to the wheels 116.

Briefly referring again to FIG. 3, the soil aeration apparatus 110 mayinclude a support shaft 124 along the central axis 121. This supportshaft 124 provides mechanical stability for the soil aeration apparatus110 when in operation. Optionally, the soil aeration apparatus 110 mayoperate without a centrally located support shaft 124. For example, thetine-holder shafts 130, 135, 140, and 145 may be rotatably mounted tothe carriers 120 and 122 so as to provide sufficient mechanicalstability for the soil aeration apparatus 110 without the need for thesupport shaft 124. In such a case, the tine-holder shafts 130, 135, 140,and 145 would also serve as non-centrally located support shafts.

Referring now to FIG. 6, the size of the soil aeration apparatus may beadvantageously reduced by eliminating the centrally located supportshaft. The soil aeration apparatus 10 (also shown in FIG. 1) includesnon-centrally located support shafts 24 and 26. As such, the tine-holdershafts 30 and 40 may be positioned closer to the central axis 21 withoutthe need for clearance space for the tines 50. The tines 50 on one shaft30 may be staggered from tines 50 on another shaft 40 such that thetines 50 may revolve about the tine-holder shaft 30 without interferencefrom other tines 50. In certain embodiments, there may be a need formechanical support from a centrally located support shaft 124. In suchcases, the tine-holder shafts may be sufficiently spaced apart such thatthe tines 50 may revolve about one tine-holder shaft withoutinterference from a centrally located support shaft or a neighboringtine-holder shaft. For example, the soil aeration apparatus 110 (alsoshown in FIG. 3) includes a centrally located support shaft 124 andtine-holder shafts 130, 135, 140, and 145 that are spaced apart toprovide clearance for the tines 50. The size of the soil aerationapparatus 110 may be reduced, however, if the centrally located supportshaft 124 is eliminated and the tine-holder shafts are positioned closerto one another.

As explained above, the size of the soil aeration apparatus 110 may bereduced if the tines 50 on one shaft 130 are staggered from tines 50 onanother shaft 135. Referring to FIGS. 7A-B, the soil aeration apparatus110 may include tine-holder shafts 130, 135, 140, and 145 that arepositioned closer to the centrally located support shaft 124 (providingonly minimal clearance between the support shaft 124 and the path ofrevolution of each tine 50). By positioning the shafts 130, 135, 140,and 145 closer to the central axis, the shafts are likewise positionedcloser to one another. In this example, the shafts 130 and 135 areattached to the carrier 120 and separated by a distance d while thetines 50 extend more than half the distance d in a radial direction fromthe shafts 130 and 135.

As shown in FIG. 7A, the closer positioning of the shafts 130, 135, 140,and 145 may cause the motion path 131 of the tines 50 on shaft 130 tooverlap the motion path 136 of the tines 50 on the neighboring shaft135. However, the tines 50 on shaft 130 are in a staggered position(shown in FIG. 1 and in FIG. 7B) relative to tines 50 on neighboringshaft 135. The staggered positioning permits the tines 50 to revolveabout the tine-holder shaft 130 without interference from tines 50 onother shafts (e.g., shaft 135). The tine-holder shafts 130, 135, 140,and 145 thus may be positioned closer to the centrally located supportshaft 124 without the potential for interference between the revolvingtines 50, thereby permitting the carrier 120 and frame 112 to havesmaller dimensions and less weight. Alternatively, a soil aerationapparatus incorporate staggered tines without a centrally locatedsupport shaft, similar to the embodiment described in connection withFIG. 1, thereby permitted the carrier 120 and frame 112 to be furtherreduced in dimension and weight.

In operation, the soil aeration apparatus 10 or 110 may be attached to aframe 12 or 112 that guides the apparatus 10 or 110 over a groundsurface. In some embodiments, the frame may be attachable to a tractoror other vehicle such that the apparatus is towed behind the vehicleover a ground surface. In other embodiments, the frame is configured tobe manually pushed by a user over the ground surface. A drive means,such as a spinning drive shaft that causes the carriers to rotate, maybe attached to the frame 12 or 112 and the soil aeration apparatus 10 or110 to produce the desired revolving and rotation motion of theplanetary gears and the tine-holder shafts. Alternatively, the drivemeans may comprise the carrier 20 or 120 being forced to rotate as itrolls along the ground surface.

Referring to FIGS. 8A-C, the soil aeration tines 50 may operate topenetrate a ground surface 80 and remove a portion of soil 82. Theinteraction of the gear system 60 and the tine-holder shafts 30 and 40causes the revolving 28 and rotation 68 motions of the tine-holdershafts 30 and 40, which in turn, causes the desired motion of theindividual tines 50. Notably, the direction of rotation 68 and thedirection revolution 28 may be different from that depicted in FIGS.8A-C, depending on a number of factors, such as the type of aerationtine 50 used with the soil aeration apparatus 10. (The operation of thesoil aeration tines 50 is described with respect to the embodiment ofthe soil aeration apparatus 10 and gear system 60 of FIG. 1, but it isunderstood that the description also applies to other embodiments of thesoil aeration apparatus, such as the embodiment shown in FIG. 3.) Thegear system 60 is configured to orient the tine 50 at an acute angle tothe ground surface 80 when the tine-holder shaft 30 is revolved 28around the center axis 21 to a point near the ground surface 80.

Referring to FIG. 8A, the soil aeration tine 50 penetrates a patch ofsoil 82 at an acute angle 84 with respect to the ground surface 80. Inthis embodiment, one or more soil fracturing surfaces 52 on the tine 50penetrate the soil at an acute angle, which causes the soil proximatethe aeration tine 50 to fracture upward rather than compact. Referringto FIG. 8B, even though the tine-holder shaft 30 continues to revolve 28around the central axis 21, the soil aeration tine 50 is rotated 68 bythe motion of the planetary gear 63 attached to the tine-holder shaft30. The sweeping action 56 from the revolving 28 and rotational 68motions forms an aeration pocket 86 in the region penetrated by the soilaeration tine 50. As shown in FIG. 8C, the tine-holder shaft 30continues to revolve 28 around the central axis 21, which causes thetine 50 to be pulled from the soil 82 even as the tine 50 continues torotate 68. The removal action 58 from the revolving 28 and rotational 68motions completes the formation of the aeration pocket 86. In thisembodiment, the tine 50 includes a cutting tube 55 that cuts and removesa plug 88 of soil 82 during the sweeping 56 and removal 58 actions. Thepenetration 54, sweeping 56, and removal 58 actions are repeated as thesubsequent tine-holder shaft 40 is revolved 28 near the ground surface80 and the corresponding planetary gear 64 causes the tines 50 to beoriented at an acute angle to the ground surface 80.

Various embodiments of the gear system for the soil aeration apparatus110 may be used to advantageously reduce the bulkiness of the apparatus110. Referring to FIG. 9, a gear system 260 may be implemented to causethe desired motion of the tine-holder shafts 130, 135, 140, and 145. Inthis embodiment, sun gear 265 is aligned with the central axis 121 andremains substantially fixed with respect to the central axis 121 even asthe carrier 120 rotates about the central axis 121. The sun gear 265 isnot necessarily positioned between the planetary gears 263 and 264, yetthe gears 263, 264, and 265 are radially aligned so that the drive chain266 may engage the gears 263, 264, and 265. Similarly, planetary gears273 and 274 interact with another sun gear (positioned behind the firstsun gear 265 and not shown in FIG. 9) that is axially aligned with thecentral axis 121. Alternatively, the drive chains 266 and 276 may engagethe same sun gear 265, depending on the axial thickness of the sun gear265 and the type of drive chain. As shown in FIG. 9, while the planetarygears 263, 264, 273, and 274 move around the corresponding sun gears inthe direction of revolution 128, each planetary gear 263, 264, 273, or274 is caused to rotate about its own axis in the direction of rotation168. Because each sun gear is used to operate a plurality of planetarygears (rather than a one-to-one correspondence), the bulkiness of thesoil aeration apparatus and gear system may be reduced.

In another embodiment, the gear system may include planetary gears thatare indirectly engaged with a sun gear. Referring to FIG. 10, a drivechain 366 engages a first planetary gear 362 and a sun gear 365. Asecondary drive chain 376 is engaged with the first planetary gear 362and other planetary gears 361, 363, and 364, but not with the sun gear365. The sun gear is axially aligned with the central axis 121 andremains substantially fixed with respect to the central axis 121 even asthe carrier 120 rotates about the central axis 121. When the carrier 120rotates about the central axis 121, the planetary gears 361, 362, 363,and 364 revolve around the sun gear 365 in the direction 128. The drivechain 366 causes the planetary gear 363 to rotate about its own axis inthe direction 168. This rotation of planetary gear 362 causes the drivechain 376 to rotate the other planetary gears 361, 363, and 364 in thesame rotational direction 168. As such, the more compact gear system 360drives four planetary gears 361, 362, 363, and 364 using an individualsun gear 365.

Certain embodiments described above show a gear system positioned on theone side of the soil aeration apparatus. Other embodiments, however, mayinclude two gear systems—one gear system positioned on each side of theapparatus. For example, one gear system may be positioned on the outerside of one carrier 20 or 120, and a second gear system (substantiallymirrored to the first gear system) may be positioned on the outer sideof the opposing carrier 22 or 122.

Furthermore, the direction of rotation 68 or 168 and the direction ofrevolution 28 or 128 are not limited to the embodiments shown in FIGS.1, 3, 4, 8A-C, 9, and 10. For example, the tines 50 that comprise soilaeration blades may be operated with the direction of rotation 68 or 168and/or the direction of revolution 28 or 128 being reversed from what isshown.

Further yet, the gear system may use an engaging member other than adrive chain to engage the gears in the gear system. For example, theengaging member may comprise a cable, belt, linked chain, or the like.Accordingly, the contact surface of the gears may be configured toappropriately engage the selected type of engaging member.

Moreover, the gear system of the soil aeration apparatus may have anynumber of sun gears, and is not limited to embodiments having one or twosun gears. Accordingly, the gear system may include any number ofplanetary gears such that each sun gear engages a plurality of planetarygears.

In another embodiment, the soil aeration apparatus may have anon-centrally located support shaft that is positioned concentricallywith a tine-holder shaft. In such an embodiment, the tine-holder shaftmay be rotatably mounted to the carrier and coupled to a planetary gearwhile an inner support shaft is fixedly coupled with respect to theopposing carriers. This arrangement of the tine-holder shaft and thenon-centrally located support shaft provides support for the soilaeration apparatus. Moreover, because the support shaft is not occupyingspace outside of the tine-holder shaft, an increased number oftine-holder shafts may be mounted to the carriers. Alternatively, thenon-centrally located support shafts may be mounted to the carriersalong the outer perimeter of the carriers. For example, in theembodiments where the carriers are circular, the support shafts may bevery thin members having a concave surface that matches the curve of thecarrier's circumference. This concave surface may be mounted to thecarrier along a portion of the circumference such that the non-centrallylocated support shaft does not occupy a significant amount of area onthe opposing faces of the carriers.

In addition, the soil aeration tines 50 are not limited to theembodiment shown in FIGS. 8A-C. Rather, the tines 50 may variousconfigurations, such as fracturing surfaces, spikes, aeration tubes,aeration blades, or a combination thereof, depending on the soil textureor other factors. Referring to FIG. 11, for example, the tines mayinclude aeration blades 150 that penetrate and cut the soil withoutnecessarily removing a “plug” of soil from the ground. The aerationblade may include a tip 152, a concave edge 154, and a convex edge 156to penetrate and cut the soil while reducing the amount of soilcompaction. As such, the ground surface is not littered with plugs ofsoil after operation of the soil aeration apparatus. For example, FIGS.12A-B provide figurative plan views of aerated soil using alternativeconfigurations of aeration tines/blades. In FIG. 12A the soil wasaerated using aeration tines 50 (depicted in FIGS. 8A-C). As the soilaeration apparatus moves over the ground surface 80 in a forwarddirection 5, the tines 50 execute the penetration, sweeping, and plugremoval actions described above to form aeration pockets 86. Each row ofaeration pockets is staggered with respect to the neighboring rowsbecause the aeration tines 50 were in a staggered position relative tothe tines on neighboring shafts (similar to the embodiment shown in FIG.7B). In FIG. 12B, the soil was aerated using aeration blades 150(depicted in FIG. 11). The aeration blades 150 form aeration pockets orgrooves 186 in the ground surface 80 to aerate the soil as the soilaeration apparatus moves in the forward direction 5. Each row of grooves186 may be staggered by staggering the position of the blades 150 onneighboring shafts (similar to the embodiment shown in FIG. 7B).Staggering the position of the aeration pockets/grooves (shown in FIGS.12A and 12B) may increase the perforation density (number of aerationpockets/slits in a given area) in the aerated soil, thus greatlyreducing soil compaction with a single pass of the soil aerationapparatus.

If the rotational velocity of the carrier holding the tine shafts isincreased relative to the tractor land speed, the pockets will belocated closer together. If desired, the pockets can overlap one anotherso that each blade forms a continuous slit. If the aeration tines haveintegral coring tubes, the carrier speed may be selected so that holesmade by the coring tubes overlap. Such an implementation would form arelatively wide and continuous slit (approximately as wide as theaeration tube). If the aeration tines are not equipped with an integralcoring tube, as shown in FIG. 11, the continuous slit would be narrower,having a width approximately matching that of the aeration tine.

The density of these staggered aeration pockets (i.e. the number ofpockets per unit area of turf) is significantly greater than thatobtained by conventional systems. In conventional aeration systems,relative to a reference aeration pocket the closest neighboring pocketis typically in line with and at least two tine lengths away from thereference pocket. The staggered tine arrangement of the presentinvention permits the rows of pockets to be offset relative to oneanother, increasing the number of pockets per unit area, as shown inFIGS. 12A and 12B.

Moreover, the aeration effect is significantly improved because thepockets are distributed more evenly across the turf by virtue of theirstaggered arrangement. Conventional systems may produce repeating rowsof coring holes having some degree of aeration, but the gap between therows is not provided any substantial aeration. To the contrary,conventional systems most often compact the soil near the coring sitebecause their tubes are forced directly down into the soil. The systemof FIG. 7, however, provides substantially uniform aeration because theresulting aeration pockets are nested together, tightly spaced, andsubstantially connected by fractures caused by the soil fracturingblades. Air, water and nutrient uptake can thereby be dramaticallyimproved.

Referring to FIGS. 14-15, the arcuate blades 150 of FIG. 11 may producea plowshare effect that serves to prevent or reduce undesirable liftingof the soil aeration apparatus from the ground surface as the aerationblades 150 penetrate compacted soil. As shown in FIG. 14, and bearing inmind that the effect of the rotational movement 128 and tractor movement119 may dominate the effect of the rotation of the arcuate tine on thetine shaft, it can be seen that the leading edge of the 150 leadingcauses the aerator frame 112 to be drawn downward. As previous describedin connection with FIG. 4, the tine-holder shafts revolve about thecentral axis 121 in the direction 128 as the planetary gear system 160causes each tine-holder shaft to rotate in the direction 168. Theaeration blades 150, which are attached to the tine-holder shafts,undergo a combined motion from the direction of revolution 128 and thedirection of rotation 168. The aeration blades 150 initially contact thesoil at an acute angle (similar to the soil penetration explain inconnection with FIG. 8A) so that the convex edge 156 is positionedgenerally below the concave edge 154 (refer, for example, to FIG. 15),and then penetrate and fracture the soil to form aeration groves. As theaeration blade 150 penetrates the ground surface 80, the angle andconfiguration of the blade 150 create a downward force, similar to thatof a plowshare as it is forced through topsoil.

Unlike conventional soil aeration systems that require additional weightstacked onto the frame, a three-point hitching system, or a limitednumber of aeration tines to prevent the apparatus from lifting off theground surface as the end-coring tines initially penetrated somecompacted soil, the plowshare effect of the arcuate blades 150 preventsor reduces such undesirable lifting. Conventional aerators typicallyrequire either significant ballast or a three point hitch system toapply a positive downward force to prevent the aerator from being liftedoff the ground as the tines impact and penetrate the ground, both ofwhich are particularly undesirable. Ballast increases the power requiredto tow the unit over turf, which in turn often necessitates the use oflarger, more expensive tractors. If the ballast weight is permanentlyattached to the unit, transport becomes difficult and expensive.Removable ballast must be stored, handled and installed, which consumestimes and almost necessarily involves a risk of injury. Three pointhitch systems, on the other hand, are expensive, complicated, andrequire more time and skill to couple to a towable device. Moreover,three point hitches must be raised off the ground before a turn is made,else the towed device will rip the turf as it swings laterally behindthe tractor. This significantly impedes any aeration operation andnecessitates the use of substantially straight aeration runs. Lastly,tractors equipped with three point hitches are themselves expensive andlarge and it is therefore more economical to use equipment that can betowed behind smaller, less expensive tractors.

Thus, a soil aerator having reduced size and reduced weight may operateusing a one-point connection to a tractor and without the need foradditional weight ballasts added onto the frame to prevent unwantedlifting off from the ground surface. Moreover, the plowshare effectpermits a greater number of arcuate blades 150 mounted on an individualtine-holder shaft to contact the ground surface at substantially thesame time with little or no lifting of the soil aerator from the ground.For example, twelve or more arcuate blades may be mounted to atine-holder having a length of approximately three feet and may contactthe ground surface at substantially the same time, similar to theembodiment shown in FIG. 4.

Accordingly, in certain embodiments the soil aeration frame 112 (FIGS.13A and 13B) does not require the application of additional downwardforce, such as ballast or a three-point hitch system to force theaerator against the ground. Rather, the soil aeration frame 112 may usea one-point connection for attachment to a tractor without the need foradditional ballast to be added onto the frame. For example, theone-point connection may be accomplished by connecting one end of aconnection shaft 118 to the utility vehicle.

As shown in FIG. 13A (and also described previously in FIG. 5), theconnection shaft 118 extends from the frame 112 and is connectable tothe vehicle at a receiving end 117. The receiving end 117 of theconnection shaft 118 may be adapted for insertion into and axiallyalignment with a complimentary shaft (not shown) on a tractor. When thereceiving end 117 is properly inserted, locking pins may be positionedin holes 117 a and 117 b to maintain that individual portion of theconnection shaft 118 in rigid attachment with the utility vehicle. Thus,the soil aeration frame 112 may receive a pulling force F from thetractor via the connection shaft 118. In another example, shown in FIG.13B, the receiving end 117 of the connection shaft 118 engages aone-point tow hitch 119 that is adapted to connect with a complimentaryball-hitch on the utility vehicle. The tow hitch 119 may be attached tothe receiving end using bolts or other fasteners through holes 117 a and117 b. In other examples, the receiving end 117 may engage the tractorusing a locking-pin/hole assembly, a male-female connector assembly, orthe like.

The tine shafts preferably have a length of about three to four feet.There are preferably at least about four tines per foot of tine shaftand if desired there may be provided six, eight, ten or more tines perfoot of tine shaft. In residential applications where tractor powerrequirements and tine replacement costs may be limiting factors, thetine count can be optionally reduced. In various embodiments havingincreased tine counts, more slender shattering knives with smallerdiameter coring tubes may be used. The shattering knives are preferablyfour to six inches long and have a width of an inch or less. The coringtubes preferably have internal diameters ranging from ¼″ to 2″,depending on the application. Any number of tine shafts may be provided,limited only by tine clearance requirements. Where variable speed drivemotors are used, two or four tine shafts are often sufficient althoughsix, eight, ten or more tine shafts may be desirable in otherembodiments with larger carriers, shorter tines and/or different drivemeans. The sun/planet gear ratio may be varied to adjust thetranslational and rotational speed of the aeration tine relative to thetractor land speed, with ratios from 1:1 to 10:1 being preferred formost applications, and ratios from 1:1 to 5:1 being most preferred intypical applications. The staggered tine arrangements may include three,four or more discrete tine shaft configurations which may be repeated onsuccessive tine shafts.

Conventional cam driven (or plunger type) aeration devices using coringtubes may not typically be towed at speeds in excess of about 1 mile perhour. At speeds greater than that, the forward motion of the tractortends to cause the coring tube to tear through the soil in the forwarddirection before it can be lifted out of the coring hole.

In contrast, however the planetary system described herein can cooperatewith the arcuate shape of the aeration tine to form a leading pocketwhich provides clearance that enables the aerator to be towed atsignificantly higher speeds without tearing through the soil at theleading edge of the aeration pocket. As shown in FIGS. 14-15, theaeration tine forms a leading pocket as the aeration tine penetrates thesoil and rotates in a clockwise direction away from the leading edge ofthe pocket. These two features separately and synergistically permit thetractor to be operated at higher speeds without the aeration tinetearing through the soil at the leading edge of the pocket. It should benoted that the rotational velocity of the carrier may be increased astractor speed increase to limit the duration of the tines' aerationsweeps. It has been observed that the planetary aeration system of FIGS.14-15 can be towed at speeds of five, ten, or even twelve miles per hourin accordance with the foregoing teachings.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A method for forming aeration pockets in a ground surface,comprising: towing an aeration apparatus that is mounted to a frame overthe ground surface using a tow vehicle, the aeration apparatusincluding: a central axis, a plurality of curved aeration bladesattached to a tine-holder shaft that is offset from the central axis,and a planetary gear system coupled to the tine-holder shaft so as todrive the curved aeration blades in a rotational motion about thetine-holder shaft and in a revolving motion about the central axis ofthe aeration apparatus as the curved aeration blades form aerationpockets in the ground surface, moving the aeration apparatus over theground surface at a substantially continuous rate of greater than aboutfive miles-per-hour while the plurality of curved aeration blades aredriven to into the ground surface and revolve about the central axis ofthe aeration apparatus in a direction toward the tow vehicle.
 2. Themethod of claim 1, further comprising connecting the frame to the towvehicle by a one-point hitch member.
 3. The method of claim 1, furthercomprising causing the curved aeration blades to penetrate the groundsurface at a predetermined orientation so as to provide a plowshareeffect that urges the frame toward the ground surface as the tow vehiclepulls the aeration apparatus over the ground surface at a substantiallycontinuous rate of greater than about five miles-per-hour
 4. The methodof claim 1, further comprising forming a plurality of substantiallycontinuous slits in the ground surface while the curved aeration bladesare driven in the rotational motion about the tine-holder shaft and inthe revolving motion about the central axis of the aeration apparatus.5. The method of claim 1, wherein each curved aeration blade comprises aconvex cutting edge and an oppositely disposed concave cutting face. 6.The method of claim 5, wherein each curved aeration blade forms anaeration pocket by cutting a groove in the ground surface.
 7. The methodof claim 1, wherein the step of moving comprises moving the aerationapparatus over the ground surface at a substantially continuous rate ofabout ten miles-per-hour or greater while the plurality of curvedaeration blades are driven to into the ground surface and revolve aboutthe central axis of the aeration apparatus in a direction toward the towvehicle.
 8. A system for forming aeration pockets in a ground surface,comprising: an aeration apparatus mounted to a frame such that the frameis operable to transport the aeration apparatus over the ground surface,the aeration apparatus having a central axis and a plurality of curvedaeration blades attached to a tine-holder shaft that is offset from thecentral axis of the aeration apparatus; and a planetary gear systemcoupled to the tine-holder shaft so as to drive the curved aerationblades in a rotational motion about a shaft axis of the tine-holdershaft and in a revolving motion about the central axis of the aerationapparatus as the curved aeration blades form aeration pockets in theground surface, wherein the aeration apparatus is movable over theground surface at a substantially continuous rate of about tenmiles-per-hour or greater while the plurality of curved aeration bladesform the aeration pockets in the ground surface.
 9. The soil aerator ofclaim 8, wherein the curved aeration blades penetrate the ground at apredetermined orientation so as to provide a plowshare effect that urgesthe frame toward the ground surface as the vehicle which transmits apulling force from the vehicle to the frame.
 10. The system of claim 8,wherein the planetary gear system drives the curved aeration blades inthe revolving motion about the central axis of the aeration apparatussuch that the curved aeration blades revolve about the central axis in adirection toward a towing vehicle connected to the frame while curvedaeration blades penetrate into the ground surface and while the aerationapparatus moves over the ground surface at the substantially continuousrate of about ten miles-per-hour or greater.
 11. The system of claim 8,wherein the frame is connectable to a tow vehicle by a one-point hitchmember.
 12. The system of claim 11, wherein the frame and the aerationapparatus is towable by the vehicle at the substantially continuous rateof about ten miles-per-hour or greater during operation while theplurality of curved aeration blades are driven to into the groundsurface and revolve about the central axis of the aeration apparatus ina direction toward the tow vehicle.
 13. The system of claim 8, whereinthe aeration apparatus forms a plurality of substantially continuousslits in the ground surface when the plurality of curved aeration bladesform the aeration pockets in the ground surface.
 14. The system of claim8, wherein each curved aeration blade comprises a blade portion having aconvex cutting edge and an oppositely dispose concave cutting edge. 15.The system of claim 8, wherein each curved aeration blade forms anaeration pocket by cutting a groove in the ground surface.